The Galileo affair before the Catholic Church by Carlos Ramos Rosete * Introduction

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1 The Galileo affair before the Catholic Church by Carlos Ramos Rosete * Introduction Galileo Galilei ( ) entered history for four reasons: 1. He set the foundations of a new Physics, discipline which would be known as Physical Mathematics. 2. The use of telescope in order to investigate the celestial bodies. 3. He looked for material evidences in order to show the physical reality of heliocentrism. 4. A conflict with the Church on account of the former. Such conflict will be known as The Galileo Affair. As to the fourth item, there has been a Manichean vision of the Galileo affair for a long time. Such vision as every Manichean vision distinguishes and separates two worlds: the one of the good and the one of the bad. Summing up such Manichean vision, we have the following: The Church would stand for the world of dogmatism, intolerance, authoritarianism, of superstitious faith keeping scientific reason in obscurity; on the other hand, Galileo would stand for the world of free, anti-dogmatic scientific research, the incipient modern rationality. Both worlds had previously collided in 1616 and definitively in 1633, when Galileo, arguing in support of heliocentrism, rejects and destroys the geocentric Catholic dogma. However, the Catholic Church, due to its inability in rational and scientific argumentation, employed the despotic power of the Holy Inquisition in order to destroy the scientific rationality which attempted against the cosmovision supported by the Church. The previous statement represents, in brief, the Manichean vision of the Galileo affair. Nevertheless, certain facts question such Manichean vision, as follows: a) Galileo has never rejected Catholic or the Church s religion. Rather, in 1616, he regretted that some theologians knew nothing of Astronomy, and, in 1633, he was the victim of a bad ecclesial policy that brought him into an unfair judgment. b) Galileo has always considered himself a faithful catholic, and according to his biographer, Vincenzio Viviani, who wrote his biography in 1654, he had a philosophical and Christian death. 1. Galileo Galilei prior to the confrontation with the Catholic Church Galileo was born on February 15 th, 1654, only four weeks after pope Pious IV approved the Council of Trent with his papal edict Benedictus Deus. In 1581, Galileo enters the University of Pisa to study Medicine. However, he was attracted to Mathematics. He gets to know the thoughts of Euclid, Archimedes and Pythagoras. In 1583, he makes statements regarding the pendulum motions, and here he polemizes with thinkers from the Aristotelian cut. According to Aristotle, bodies possess three natural motions: upward, due to fire and air; downward, thanks to earth and water, and finally, the circular motion proper of celestial bodies. If this is so, then, following Aristotle s thought, pendulous motion would be unnatural. However, Galileo discovered that the pendulum motion, in fact, obeys an order. Galileo reasons as follows: if one makes a pendulum, when he puts it into movement, he observes that the time for each oscillation will always be the same, although the oscillations amplitude decreases; so, how can an unnatural movement, according to Aristotle, have a mathematical order? Rather, Galileo thinks, the Aristotelian distinction on the natural motions of upward, downward and circular is insufficient. In 1585, Galileo writes, in Latin, Theorems on the Centre of Gravity of Solids, where he makes studies on the specific weight of bodies. In 1586 he writes The Little Balance where he displays the related towards the hydrostatic balance. In 1589 he achieves a cathedra of Mathematics in the University of Pisa. At his farm in Pisa, Galileo begins to make observations regarding the free-fall of bodies and again he collides with Aristotle, because, according to the Stagirite, it was an obvious fact that in the fall of bodies with different weights, the heavier one should fall with greater speed than the lighter one; for example, a me- 44

2 tal piece should fall with greater speed than a piece of paper. In face of this, Galileo reasoned, the obvious fact that the heavier body reaches the ground first and the lighter one reaches it later, does not necessarily mean that they fall with the same speed; in fact, the heavier body can cut air resistance more easily and thus arrives first to the floor; instead, the lighter body has more difficulty in breaking air resistance and thus arrives later. So, if we ignore air resistance, all bodies fall at the same speed. Galileo s experiences on freefall motion prove him right and refute Aristotle. In 1590 he writes a treaty on motion entitled De motu. In 1592 he goes to the University of Padua to teach Mathematics. There he will remain for eighteen years. Around 1595, Galileo knows Ptolemy s astronomic system rather well, for he makes a comment on the Almagesto. One may say that, since the end of the 16 th century and beginning of the 17 th, he starts using the Copernican system as a less complex mathematical and geometrical system than the Ptolemaic one for describing celestial motions. In 1604, a new star appeared that was actually a supernova. Such phenomenon put under judgment the Aristotelian idea on the immutability of the skies. Due to this, polemics were unleashed: if the celestial phenomenon in sight was actually a celestial phenomenon, it contradicted the Aristotelian idea on the skies; or rather, such phenomenon should be interpreted as happening in the high layers of earthly atmosphere, thus saving the Aristotelian immutability of the skies. 2. Astronomy at the light of the telescope In the end of the 16 th century, some lense devices appeared enabling far-off sight, for they increased the size of distant objects; such instruments were used by the army, or displayed in exhibitions as curious objects. It seems that around 1608 and 1609 Galileo takes notice of such devices and, improving one of them, he manages to conceive a telescope. This is the inedited about Galileo: to use for scientific purposes a device of practical use. In the fall and winter of 1609, he makes his first telescopic observations, which can be synthesized the following way: Observation of the existence of new stars never seen before. The universe is larger than we think. In a heliocentric system the universe is wider than in a geocentric one, because in the heliocentric system fixed stars must be further away from the earth in order to explain the movements and positions of celestial bodies; which refutes the Ptolemaic idea that fixed stars are immediately beyond the planet Saturn. Now, with such observation, Galileo supports the idea of the probable physical reality of heliocentrism. The Moon s surface is similar to the Earth s. With this he dismantles the Aristotelian-like idea that the Moon has such a smooth surface that it causes the reflection of the sun light. Our galaxy is a set of stars. Therefore, galaxies are not stellar clouds. Jupiter has four moons, which utterly proves that the idea of a planet rotating around a centre, followed by its satellite(s), cannot be considered false, whether in a geocentric or heliocentric system. So, in March, 1610, Galileo publishes a work entitled Sidereus nuncios (the celestial messenger). This was the first work in human history where someone speaks of stars based on telescopic observations. Between 1611 and 1615, Galileo makes new observations: The three-dimensional aspect of Saturn. Phases in Venus. That is, the planet Venus presents phases when it is illuminated by the Sun, similarly to the Moon. The question here is that, according to the geocentric system, Venus should not present phases, but in a heliocentric system Venus phases are perfectly compatible with it. The Sun presents periodical spots. Therefore, there are qualitative changes in the Sun, unforeseen by Aristotle. 3. The controversy: geocentrism versus heliocentrism In 1612 Galileo publishes his Discourse on bodies that stay atop water, or move in it. The appearance of this writing was motivated by a polemics that happened during a supper on the night of October 2 nd, The explanation regarding floating bodies, following Aristotle, appealed to the shape or aspect of the bodies, that is, if a body floated that was because it had a certain shape or aspect. Concretely, the explanation for the floating ice, according to Aristotle, was as follows: ice is heavier than water, however, the ice pieces float because of their large and flattened shape, which prevents the ice from penetrating the liquid s surface, thus not sinking. 45

3 Galileo, following Archimedes, knew that ice was less dense than water and, therefore, lighter, hence it would always float no matter what its shape and aspect are. He proved this by submerging a piece and letting it go underwater so it could surface. In 1613 he publishes the Letter on the solar spots. Already in Florence, he proceeds with his astronomical researches, but, at the same time, his adherence to Copernicanism together with its material evidences, the discovery of Jupiter s four moons and the phases of Venus cause him serious troubles with those theologians who supported the Ptolemaic system. The controversy between heliocentrism and geocentrism brought three aspects: a) Physical: the main objections to heliocentrism were focused on problems regarding gravity. Although Galileo responded to them by adding good examples, such as the boat s motion and the behavior bodies had in it, he failed by not having a theory of gravity. This was achieved by Isaac Newton through the Theory of Universal Gravitation, later in 1687, in his work Mathematical Principles of Natural Philosophy. Given this limitation, Galileo even argued that the tides (high tide and low tide) were the consequence of Earth s rotation and translation movements, which was later proven to be false. b) Mathematical: the planets movements, as we know, are elliptical. Galileo thought, instead, the planets followed a circular route. This presented him with difficulties to mathematically and geometrically justify heliocentrism. Galileo haughtingly considered that Johannes Kepler was wrong in his idea of elliptic orbits. c) Theological: there are certain passages from the Holy Scriptures that point toward geocentrism, as follows: 1. Psalm 104,5 (Non-moving Earth) 2. Psalm 95,5 (Non-moving Earth) 3. I Chronicles 16,30 (Non-moving Earth) 4. Ecclesiastes 1,5 (Moving Sun) 5. Genesis 1,16-18 (Earth at the centre) 6. Joshua (Sun and Moon movements) Therefore, the heliocentrism versus geocentrism controversy created polemics in Physics, Mathematics, and Theology. Between 1613 and 1615, Galileo writes the four Copernican letters, where he displays his points of view on the theological controversy. Grosso modo, in those letters Galileo explains: a) The Holy Scripture cannot be mistaken and its decrees are utterly correct and inviolable. b) The Holy Scripture teaches us how to get to heaven, not how heaven works. For Galileo, the heliocentrism versus geocentrism controversy is not a religious question, but merely a cosmological one. The Holy Scripture is not fit to solve such controversy. c) If it is not the Holy Scripture s aim to teach us how heaven works, with this statement Galileo begins to affirm Astronomy s autonomy from Theology, which the Medieval thought to be the queen of sciences. d) Galileo thinks that the biblical passages of geocentric kind must be interpreted symbolically, not literally, and hence he argues that if the Bible was always to be literally interpreted to the letter one would fall into many contradictions, including serious heresies and blasphemies since it would be necessary to attribute God hands, feet, and human and bodily feelings, such as anger, pain, hate, and even the most absolute oblivion of the past and complete ignorance of the future. With this, Galileo begins to tell theologians how they should interpret the Bible regarding the geocentric passages, that is, in a symbolic fashion. e) Galileo shows that truth does not contradict truth; the Holy Scripture s truth does not contradict Astronomy s truth, for the Holy Scripture comes from the Holy Spirit, who is God, and the study of Astronomy comes from nature, which is the work of God. f) If there is a mistake, it is the theologians or the astronomers mistake. In this polemics, an ecclesiastical figure known as Cardinal Roberto Bellarmino ( ) stood out when noticing that the collision between Aristotelians and Galileo was increasing its tone. He warned Galileo of the following: 1. To exchange the literal sense of some Bible passages by a symbolic interpretation is a very delicate issue, because the holy Fathers tradition and the present interpretation coincide in displaying them literally. 2. Although the geocentrism of such passages is not a faith dogma, as, for example, Christ s Incarnation or Resurrection are, even so it regards faith, ex parte dicentis, something said from faith or deriving from faith. 3. In case there was an utter demonstration of heliocentrism, then that would demand a reinterpretation of Scriptures, but only in the condition that there was such demonstration. 46

4 4. Traditional Philosophy and Astronomy affirm the geocentric truth. 5. He proposes to interpret heliocentrism in an exclusively mathematical fashion, leaving aside its physical aspect. 4. The confrontation with church in 1616 On February 7 th, 1615, Dominican Nicollo Lorini denounces Galileo before the Holy Office sending a copy of one of the Copernican letters, namely the one of Benedetto Castelli, and drawing attention to some of the dangerous propositions, as follows: a) Galileo declares that some of the Holy Scripture s speeches are not valid. b) Galileo declares the Holy Scriptures occupy the last place as to the knowledge of natural things. c) Galileo declares that the Holy Scriptures refer only to faith and do not teach on creation. d) Galileo declares that in natural things mathematical argumentation is superior to the Holy Scriptures. On February 19 th, 1616, Galileo is inquired by the Holy Office s court for the possible crime of heresy due to the following theses: a) That the Sun is the centre of the world and, hence, lacking local motion. b) That the Earth is neither at the centre of the world nor without motion, but that it moves entirely around itself in an everyday movement. On February 24 th, 1616, six theologians examined the previous two theses and unanimously reached the following resolutions: a) The first thesis: it was philosophically foolish and absurd, and formally heretic in the sense that it contradicted the Holy Scripture s sayings in their literal meaning and according to the general commentary from the holy Fathers and the Doctors of the Church. b) The second thesis: it was philosophically foolish and absurd, and, at least theologically wrong concerning faith. On February 26 th, 1616, Cardinal Bellarmino sends Galileo an admonition on behalf of the Holy Office and the Holy Father. He also forbids Galileo from teaching heliocentrism, whether orally or in writing, and exhorts him to abandon the heliocentric theory under the penalty of being prosecuted in case of relapsing. Next, they issued an official register where Galileo pledges himself not to teach heliocentrism. On March 3 rd, 1616, the Holy Office sent its sentence to the Congregation of the Index and this congregation issued a condemnation of the Copernican system due to its attempt against the Holy Scripture. Such condemnation textually stated that Copernicanism was contrary to the Holy Scriptures In 1623, Galileo publishes a work known as The Assayer on the nature of comets, which he considers as atmospheric phenomena, and therefore non-celestial; besides, this is a work where he deals with questions concerning the new Physics and gives it methodological guidelines. In this work, Galileo writes: This grand book, the universe [ ] is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it. On August 6 th, 1623, under the name of Urban VIII, pope Maffeo Barberini, a friend of Galileo s, is elected, and in April 1624 Galileo has six private meetings with this pope, a man interested in scientific issues and even in heliocentrism. 5. The dialogue concerning the two chief systems of the world From 1624 to 1639, Galileo proceeds with his private research in order to better found his heliocentric ideas and prepares a work that he will publish in 1623, entitled: Dialogue by Galileo Galilei Linceo, honorary mathematician at the University of Pisa and philosopher and master mathematician of his most serene highness the great duke of Tuscany. Where in the period of four journeys we argue on the two chief systems of the world: the Ptolemaic and the Copernican, and we expose without final conclusion the physical and philosophical reasons from one party and the other. The characteristics of such dialogues are: 1. Written in Italian, not Latin. With that, Galileo was trying to reach not only the learned public, but also the general one. 2. It was written in the form of dialogues among three characters. 3. The three characters are: Salviati, Sagredo, and Simplicio. Salviati stands for the Copernican scientist, cautious but determined, patient but tenacious, deep down it was the very Galileo arguing. Sagredo stands for the public open to novelties, but who wishes to know the reasons from both parties. Simplicio stands for the Aristotelian philosopher, the defender of traditional knowledge of geocentric kind. 47

5 In the work s preface, Galileo announces an objective debate where he is to call into question the Copernican theory as mathematical hypothesis. However, when reading the work s body especially the third and fourth journeys it is easy to notice that it is a work in favor of heliocentrism, enhancing Copernicus merits and Ptolemy s defects. The dialogue lasts for four journeys of conversation where the distinction of the twofold Aristotelian Physics, celestial world and earthly world, is criticized, reaching the conclusion that there is only one Physics. Arguments in favor of geocentrism and against heliocentrism are confronted displaying the frailty of arguments in favor of geocentrism and proving that the arguments against heliocentrism make no sense at all. In the conclusion, he closes by saying that heliocentrism is perhaps false as a physical reality, so that the book was not rejected by the ecclesiastical review that granted the imprimatur. 6. Galileo s trial in 1633 In the beginning of 1632, the book starts to be printed and sold. In May, 1632, it is confiscated in Rome due to the following reasons: 1 Galileo proposes the Earth s movement and the Sun s immobility as physical truths; 2 He did not keep his 1616 s pledge of not divulgating heliocentrism; 3 The book was written in common language and not in Latin, with which the error would be disseminated. In Rome, there was even a division among the clergymen themselves: some agreed with the book s content and others did not. The polemics in favor or against Galileo and his book was so important in Rome that even pope Urban VIII, in 1632, designated a Commission to investigate the matter. The Commission ratified the three previous reasons, and added a fourth. According to it, certain irregularities had been detected, preventing the grant of the imprimatur, that mister Galileo had pledged himself to correct, but never did. Pope Urban VIII sent the results to the Court of the Holy Office, and on October 3 rd, 1632 the court summoned Galileo to be judged as a propagator of heresies. On February 13 th, 1633, Galileo arrives in Rome to be judged. From February to June, Galileo was submitted to four inquiries, so that, finally, on June 22 nd, 1633 the final judgement occurred. Three out of ten judges claimed Galileo was not guilty. The penalty implied prison, but due to Galileo s old age, it was commuted into house arrest in his villa in Florence, where he should spend the rest of his life, receiving no guests without previous permit. This villa was beside Saint Matthew s Monastery, where his daughter, Sister Maria Celeste, was. 7. Galileo s last stage After the second trial and his retraction, Galileo writes Discourses and mathematical demonstrations concerning two new sciences pertaining to mechanics and local motion. The Discourses were written also in a dialogue format and there we find the same protagonists of the Dialogue concerning the two chief systems: Salviati, Sagredo, and Simplicio. The Discourses are also displayed in four journeys. In the first two journeys, the discussion is about the resistance of materials. Galileo also makes a recount and seeks to ground all his researches in Physics more precisely: vacuum, free-fall, pendulum laws. He also develops issues about Statics the first new science. The third and fourth journeys are dedicated to a second new science: Dynamics. There he speaks of the uniform motion, the naturally accelerated motion and the uniformly accelerated motion; and he also establishes that a projectile s trajectory has a parabolic format. The Discourses were printed in Holland, where they had arrived in an underhand fashion and appear in They represent Galileo s most mature and original contribution, setting the bases of modern Physics that will be grounded and developed by Newton. Bibliography SOBEL, Dava. La hija de Galileo; una nueva visión de la vida y obra de Galileo. Madrid, Debate, FISCHER, Klaus. Galileo Galilei. Barcelona, Herder, BRANDMULLER, Walter. Galileo y la Iglesia. Madrid, Rialp, REALE, Giovanni & ANTISERIM, Darío. Historia del pensamiento filosófico y científico. Tomo II. Barcelona, Herder, Version by Carlos Manuel Miranda Leite da Silva Notes * Licensed in Philosophy by the Autonomous Popular University of the State of Puebla. Master s degree in Philosophy by the University of Valle de Atemajac. Author of the book Introducción a la cosmovisión náhuatl, published by UPAEP. 48